A biochemical hypothesis on the formation of fingerprints using a turing patterns approach

Non-equilibrium-Growing Aesthetic Ionic Skin for Fingertip-Like Strain-Undisturbed Tactile Sensation and Texture Recognition

Humans use periodically ridged fingertips to precisely perceive the characteristics of objects via ion-based fast- and slow-adaptive mechanotransduction. However, designing artificial ionic skins with fingertip-like tactile capabilities remains challenging because of the contradiction between structural compliance and pressure sensing accuracy (e.g., anti-interference from stretch and texture recognition). Inspired by the formation and modulus-contrast hierarchical structure of fingertips, an aesthetic ionic skin grown from a non-equilibrium Liesegang patterning process is introduced. This ionic skin with periodic stiff ridges embedded in a soft hydrogel matrix enables strain-undisturbed triboelectric dynamic pressure sensing as well as vibrotactile texture recognition. By coupling with another piezoresistive ionogel, an artificial tactile sensory system is further fabricated as a soft robotic skin to mimic the simultaneous fast- and slow-adaptive multimodal sensations of fingers in grasping actions. This approach may inspire the future design of high-performance ionic tactile sensors for intelligent applications in soft robotics and prosthetics.

Rete ridges: Morphogenesis, function, regulation, and reconstruction

Rete ridges (RRs) are distinct undulating microstructures at the junction of the dermis and epidermis in the skin of humans and certain animals. This structure is essential for enhancing the mechanical characteristics of skin and preserving homeostasis. With the development of tissue engineering and regenerative medicine, artificial skin grafts have made great progress in the field of skin healing. However, the restoration of RRs has been often disregarded or absent in artificial skin grafts, which potentially compromise the efficacy of tissue repair and regeneration. Therefore, this review collates recent research advances in understanding the structural features, function, morphogenesis, influencing factors, and reconstruction strategies pertaining to RRs. In addition, the preparation methods and limitations of tissue-engineered skin with RRs are discussed. STATEMENT OF SIGNIFICANCE: The technology for the development of tissue-engineered skin (TES) is widely studied and reported; however, the preparation of TES containing rete ridges (RRs) is often ignored, with no literature reviews on the structural reconstruction of RRs. This review focuses on the progress pertaining to RRs and focuses on the reconstruction methods for RRs. In addition, it discusses the limitations of existing reconstruction methods. Therefore, this review could be a valuable reference for transferring TES with RR structure from the laboratory to clinical applications in skin repair.

Information Hiding Based on Statistical Features of Self-Organizing Patterns

A computational technique for the determination of optimal hiding conditions of a digital image in a self-organizing pattern is presented in this paper. Three statistical features of the developing pattern (the Wada index based on the weighted and truncated Shannon entropy, the mean of the brightness of the pattern, and the p-value of the Kolmogorov-Smirnov criterion for the normality testing of the distribution function) are used for that purpose. The transition from the small-scale chaos of the initial conditions to the large-scale chaos of the developed pattern is observed during the evolution of the self-organizing system. Computational experiments are performed with the stripe-type patterns, spot-type patterns, and unstable patterns. It appears that optimal image hiding conditions are secured when the Wada index stabilizes after the initial decline, the mean of the brightness of the pattern remains stable before dropping down significantly below the average, and the p-value indicates that the distribution becomes Gaussian.

Limb development genes underlie variation in human fingerprint patterns

Fingerprints are of long-standing practical and cultural interest, but little is known about the mechanisms that underlie their variation. Using genome-wide scans in Han Chinese cohorts, we identified 18 loci associated with fingerprint type across the digits, including a genetic basis for the long-recognized “pattern-block” correlations among the middle three digits. In particular, we identified a variant near EVI1 that alters regulatory activity and established a role for EVI1 in dermatoglyph patterning in mice. Dynamic EVI1 expression during human development supports its role in shaping the limbs and digits, rather than influencing skin patterning directly. Trans-ethnic meta-analysis identified 43 fingerprint-associated loci, with nearby genes being strongly enriched for general limb development pathways. We also found that fingerprint patterns were genetically correlated with hand proportions. Taken together, these findings support the key role of limb development genes in influencing the outcome of fingerprint patterning.

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GWAS identifies variants associated with fingerprint type across all digits

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Fingerprint-associated genes are strongly enriched for limb development functions

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Evi1 alters dermatoglyphs in mice by modulating limb rather than skin development

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Fingerprint patterns are genetically correlated with hand and finger proportions

Towards Construction Based Data Hiding: From Secrets to Fingerprint Images

Data hiding usually involves the alteration of a cover signal for embedding a secret message. In this paper, we propose a construction based data hiding technique which transforms a secret message into a fingerprint image directly. Unlike the conventional data hiding techniques, this scheme does not need any cover signals to participate. Instead, it generates the fingerprint image based on a piece of hologram phase constructed from the secret message. The hologram phase consists of the spiral phase and the continuous phase. Firstly, we propose to map the secret message to a polynomial and encode it into a set of points with different polarities, from which the spiral phase is computed and constructed. Then, we construct the continuous phase by decomposing a fingerprint image synthetically generated. The spiral phase and the continuous phase are combined to form the hologram phase. This is eventually used to construct a fingerprint image in a common form such as a grayscale fingerprint image, a binary fingerprint image, or a thinned fingerprint image. The secret message can be extracted by detecting the encoded points in the constructed fingerprint. We conduct the experiments by constructing fingerprint images with ordinary sizes, the results show that the secret message can be extracted accurately. It is also difficult to detect the existence of secret message from the constructed fingerprint images.

Growth of the flat bones of the membranous neurocranium: a computational model

This article assumes two stages in the formation of the bones in the calvaria, the first one takes into account the formation of the primary centers of ossification. This step counts on the differentiation from mesenchymal cells into osteoblasts. A molecular mechanism is used based on a system of reaction-diffusion between two antagonistic molecules, which are BMP2 and Noggin. To this effect we used equations whose behavior allows finding Turing patterns that determine the location of the primary centers. In the second step of the model we used a molecule that is expressed by osteoblasts, called Dxl5 and that is expressed from the osteoblasts of each flat bone. This molecule allows bone growth through its borders through cell differentiation adjacent to each bone of the skull. The model has been implemented numerically using the finite element method. The results allow us to observe a good approximation of the formation of flat bones of the membranous skull as well as the formation of fontanelles and sutures.

A theoretical model of dentinogenesis: dentin and dentinal tubule formation

INTRODUCTION

Dentinogenesis, odontoblast dentin formation, includes dentinal growth, mineralization and dentinal tubule formation. Odontoblasts synthesize collagen resulting in collagen apposition contributing to dentinogenesis. Furthermore, within the tubule, they express non-collagenous proteins, such as dentin phosphoprotein (DPP), associated with hydroxyapatite crystal formation and growth. The aim of this work was to determine patterns of growth and dentin formation and quantification of its mineralization. Findings from our work are relevant to endodontics for future regenerative treatment.

METHODS

We formulated a 3D domain mathematical model, which recreates the events that lead to dentinal tubule mineralization. As reference we used collagen apposition and DPP activity.

RESULTS

We obtained a model depicting predentin's mineralization distribution during dentin development. Furthermore, we verified different DPP diffusion coefficients to test the model's sensitivity.

CONCLUSIONS

We present a model to shed light on the process of dentin and dentinal tubule formation, and its relation to diffusion and mineralization processes.

Spongiosa primary development: a biochemical hypothesis by Turing patterns formations

We propose a biochemical model describing the formation of primary spongiosa architecture through a bioregulatory model by metalloproteinase 13 (MMP13) and vascular endothelial growth factor (VEGF). It is assumed that MMP13 regulates cartilage degradation and the VEGF allows vascularization and advances in the ossification front through the presence of osteoblasts. The coupling of this set of molecules is represented by reaction-diffusion equations with parameters in the Turing space, creating a stable spatiotemporal pattern that leads to the formation of the trabeculae present in the spongy tissue. Experimental evidence has shown that the MMP13 regulates VEGF formation, and it is assumed that VEGF negatively regulates MMP13 formation. Thus, the patterns obtained by ossification may represent the primary spongiosa formation during endochondral ossification. Moreover, for the numerical solution, we used the finite element method with the Newton-Raphson method to approximate partial differential nonlinear equations. Ossification patterns obtained may represent the primary spongiosa formation during endochondral ossification.